Resolving CEMAT Interlock Window Display Failures on OS Clients: Multiple C_INTER5 Navigation and Server Prefixes

When multiple C_INTER5 (or C_INTERL) interlock blocks are cascaded and assigned to a single CEMAT object (such as C_DRV_1D parameter ESVG), all interlock boxes open successfully on the OS Server, but only the first box opens on OS Clients because the secondary faceplate invocation script fails to resolve the WinCC Server Prefix. On OS Clients, nested faceplate scripts require the explicit server package name prepended to tag paths. To resolve this, ensure the OS Server package is updated on all clients, verify that client project folders contain the latest CEMAT client script binaries in GraCS, and configure the interlock chaining parameter LNK_INT to allow multi-window client resolution.

CEMAT Multi-Interlock Architecture: Cascading C_INTER5 Blocks

In plants governed by the CEMAT Minerals library (cement plants, quarries, bulk loading ports), industrial equipment such as kiln drives, raw mill fans, and clinker conveyors require complex protection logic. Standard CEMAT interlock blocks (C_INTER5 or C_INTERL) provide 5 digital inputs each (I1 to I5).

When a machine requires 10 or 15 protection permissives (e.g., motor bearing vibration, winding temperature, cooling water flow, emergency pull-wire), engineers cascade multiple C_INTER5 blocks together. In CEMAT faceplate navigation, clicking the protection interlock button (ESVG) should open a hierarchical sequence of interlock diagnostic popups allowing operators to inspect every upstream condition.

Why Secondary Interlock Windows Fail on OS Clients vs OS Servers

A persistent field issue arises where the entire chain of C_INTER5 windows opens perfectly on the OS Server, but on OS Clients, only the very first C_INTER5 window appears; clicking further reveals nothing.

This discrepancy is rooted in WinCC client-server architecture:

On the OS Server: All tags reside locally in the native SQL database. When the CEMAT C-script opens @PG_C_INTER5.pdl, it reads raw tag names directly and evaluates interconnected block tags without path translation.
On the OS Client: The client does not possess local tags. Every tag must be prefixed with the Server Prefix (e.g., OS_RMS::Plant/Area/Drive_ESVG_IL2). While the primary faceplate manager injects the server prefix into the first window, older or unpatched CEMAT scripts fail to propagate the server prefix to secondary child windows, causing the client window manager to abort silently due to 'Tag not found'.

WinCC Server Prefix Mechanics in Distributed Client-Server Systems

To navigate nested faceplates on an OS Client, the script initiating the secondary popup must execute:

char szServerPrefix[64];
GetServerPrefix(lpszPictureName, szServerPrefix, sizeof(szServerPrefix));
// Prepend szServerPrefix to secondary C_INTER5 tag path

If the client project was commissioned without running the CEMAT Client Project Editor or if server data packages are stale, the client script receives an empty string for the server prefix, attempting to find the tag locally on the client.

Step-by-Step Procedure to Enable Multi-Interlock Client Navigation

Follow this sequence to restore multi-interlock navigation on all OS Clients:

Compile Server Data on OS Server: In SIMATIC Manager, right-click the OS Server project and select Compile OS. Confirm that a fresh .pck package is generated in the server's Packages folder.
Update Server Package on Clients: Open each OS Client project in WinCC Explorer. Expand Server Data. Right-click the server package and select Update. Ensure the option 'Implicit update' is enabled.
Synchronize CEMAT Client Graphics (GraCS): In SIMATIC Manager, run the CEMAT OS Project Editor on all OS Clients. This ensures that @PG_C_INTER5.PDL and related faceplate scripts (C_*.fct) are updated to the latest revision containing server prefix inheritance.
Configure Block Interconnection (LNK_INT): In CFC, ensure that cascaded C_INTER5 blocks interconnect via the designated link pins (LNK_INT or structure pointer), which allows the CEMAT driver generator to create valid pointer tags in WinCC.
Download to OS Clients: Download the updated OS Client projects. Deactivate and reactivate WinCC Runtime.

CEMAT Faceplate Window Manager Resolution Matrix

The following table compares faceplate window behaviors on OS Servers versus OS Clients:

Station EnvironmentPrimary Faceplate (C_DRV_1D)First Interlock Box (C_INTER5)Secondary Cascaded BoxRoot Cause if Secondary FailsOS Server (Local)Opens normallyOpens normallyOpens normallyLocal SQL tags resolved without prefixOS Client (Standard)Opens normallyOpens normallyFails to openMissing server prefix in child scriptOS Client (Patched)Opens normallyOpens normallyOpens normallyServer prefix inherited across child windowsWebNavigator ClientOpens normallyOpens normallyConditionalRequires WebNavigator CEMAT publisher run

Verification

Verify multi-interlock navigation across all stations through the following steps:

Log onto an OS Client in the central control room.
Click the motor icon to open @PG_C_DRV_1D.PDL.
Click the protection interlock button ESVG. Confirm that the first C_INTER5 faceplate opens.
In the first interlock faceplate, click the cascaded link button leading to the second C_INTER5 block.
Confirm that the second C_INTER5 popup opens immediately, displaying live digital inputs I1 through I5 with green/yellow status LEDs.
Verify that no script errors appear in WinCC APDiag or the diagnostic trace log.

Limitations and Operational Precautions

Consider these operational rules when configuring CEMAT interlocks:

Maximum Cascading Depth: Avoid cascading more than three C_INTER5 blocks in series (15 inputs); excessive nesting confuses operators during emergency trip situations. For very large interlock matrices, use APL Intlk16.
Never Edit Client GraCS Locally: Always update system faceplates from the Engineering Station and download to clients; local modifications in client GraCS will be overwritten by future OS compilations.
Server Redundancy Parity: Ensure both redundant OS Servers have identical server packages loaded on clients to avoid navigation dropouts during server redundancy failover.

Engineer FAQ

What does the LNK_INT pin do on CEMAT interlock blocks?

LNK_INT establishes a structural pointer between cascaded interlock blocks so the AS-OS compiler can link faceplate navigation trees in WinCC.

How many inputs does C_INTER5 provide?

C_INTER5 provides 5 digital interlock inputs (I1 to I5), each with configurable inversion and bypass parameters.

Where can I find script error logs on an OS Client?

Check <WinCC_Project_Directory>\Diagnostics\ or launch apdiag.exe from the WinCC bin directory to view real-time C-script and VBScript execution errors.